Google Open-Sources Agent Executor (AX): Distributed Runtime with Durable Execution and Trajectory Branching

Google Cloud Blog·high signal

Google released Agent Executor (AX) on May 20 as an open-source distributed agent runtime on GitHub (google/ax) designed for long-running agent workflows that persist hours or days. Key capabilities include durable execution with automatic resume via event logs and snapshotting, trajectory branching that checkpoints workflows for testing different execution paths, and session consistency via a single-writer architecture. Agent Substrate, announced simultaneously, introduces a Kubernetes abstraction layer designed for hundreds of millions of registered agents and millions of sub-second tool calls.